Xamarin表单IOS“Entry”是不可编辑的

我正在使用Xamarin.Forms来构建我的应用程序 . 在登录页面中，我有以下布局

<ScrollView>
    <Grid 
        RowSpacing="{StaticResource MediumSpacing}" 
        ColumnSpacing="{StaticResource MediumSpacing}">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--Two stackLayouts-->

        <!--StackLayout 1-->
        <StackLayout Spacing="0" Padding="0">
            <!--Three stacklouts here-->
            <!--First-->
            <StackLayout>
                <StackLayout.Spacing>
                    <OnPlatform x:TypeArguments="x:Double" Android="12" iOS="30" WinPhone="12"/>
                </StackLayout.Spacing>
                <StackLayout.Padding>
                    <OnPlatform x:TypeArguments="Thickness" Android="32,24,32,24" iOS="16,24,16,24" WinPhone="32,24"/>
                </StackLayout.Padding>
                <imagecircle:CircleImage
                    HorizontalOptions="Center"
                    VerticalOptions="Center"
                    WidthRequest="95" HeightRequest="95"
                    BorderColor="{StaticResource Primary}"
                    Aspect="AspectFill"
                    x:Name="CircleImageAvatar"/>

                <Label HorizontalTextAlignment="Center"
                   HorizontalOptions="FillAndExpand"
                   StyleId="LoginPageIdentifier"
                   LineBreakMode="WordWrap"
                   FontSize="Large"
                   TextColor="{DynamicResource DetailTextColor}"
                   Text="Single Sign On">

                    <Label.FontSize>
                        <OnPlatform x:TypeArguments="x:Double" Android="15" iOS="15" WinPhone="15"/>
                    </Label.FontSize>
                </Label>
            </StackLayout>
            <!--Second Stack Layout-->
            <StackLayout>
                <StackLayout.Padding>
                    <OnPlatform x:TypeArguments="Thickness" Android="32,0" iOS="32,0" WinPhone="32,0"/>
                </StackLayout.Padding>
                <StackLayout.Spacing>
                    <OnPlatform x:TypeArguments="x:Double" Android="0" iOS="15" WinPhone="10"/>
                </StackLayout.Spacing>
                <toolkit:EntryLine
                   Text="{Binding Email}" 
                   Keyboard="Email"
                   HorizontalOptions="FillAndExpand"
                   Placeholder="Email Address"
                   x:Name="EntryEmail"
                   StyleId="EmailTextField"

                   BorderColor="#ECECEC">
                    <toolkit:EntryLine.HorizontalTextAlignment>
                        <OnPlatform x:TypeArguments="TextAlignment" iOS="Center"/>
                    </toolkit:EntryLine.HorizontalTextAlignment>
                </toolkit:EntryLine>

                <toolkit:EntryLine 
                   Text="{Binding NamespaceUri}" 
                   HorizontalOptions="FillAndExpand"
                   HorizontalTextAlignment="Center"
                   Placeholder="Namespace"
                   StyleId="EmailTextField"
                   Keyboard="Text"
                   BorderColor="#ECECEC">
                    <toolkit:EntryLine.HorizontalTextAlignment>
                        <OnPlatform x:TypeArguments="TextAlignment" iOS="Center"/>
                    </toolkit:EntryLine.HorizontalTextAlignment>
                </toolkit:EntryLine>
            </StackLayout>
            <!--Third Stack Layout-->
            <StackLayout>
                <StackLayout.Padding>
                    <OnPlatform x:TypeArguments="Thickness" Android="32,16,32,0" iOS="32,25,32,0" WinPhone="32,16,32,0"/>
                </StackLayout.Padding>
                <StackLayout.Spacing>
                    <OnPlatform x:TypeArguments="x:Double" Android="0" iOS="16" WinPhone="10"/>
                </StackLayout.Spacing>
                <Button 
                Text="Sign In"
                Command="{Binding LoginCommandSso}"
                HorizontalOptions="FillAndExpand"
                StyleId="SignInButton"
                TextColor="White"
                BackgroundColor="{StaticResource Primary}">

                    <Button.FontAttributes>
                        <OnPlatform x:TypeArguments="FontAttributes" iOS="Bold"/>
                    </Button.FontAttributes>
                </Button>

            </StackLayout>
        </StackLayout>

        <!--StackLayout 2-->
        <!--Contains activity indicator and Corresponding label-->
        <AbsoluteLayout>
            <StackLayout 
        Grid.Row="1" 
        Padding="16,0" 
        VerticalOptions="Center" 
        Orientation="Horizontal"
        HorizontalOptions="Center"
        AbsoluteLayout.LayoutFlags="PositionProportional"
        AbsoluteLayout.LayoutBounds="0.5,0.5,-1,-1"
        IsVisible="{Binding IsBusy}">
                <ActivityIndicator IsRunning="{Binding IsBusy}">
                    <ActivityIndicator.Color>
                        <OnPlatform x:TypeArguments="Color" Android="{StaticResource Primary}"/>
                    </ActivityIndicator.Color>
                </ActivityIndicator>
                <Label Text="{Binding Message}" VerticalOptions="Center"  HorizontalOptions="Center" />
            </StackLayout>
        </AbsoluteLayout>
        <!--Stack Layout 3-->

    </Grid>
</ScrollView>

在Android模拟器上运行时，我可以在"EntryLine"中输入文本，一切似乎都能正常工作 . 但是，当我试图在IOS模拟器上运行它时，文本变得不可用，即只读 . 基本上在IOS模拟器上，StackLayout内部的一切都变成了"ReadOnly" I also tried using forms "Entry" instead of FormsToolKit.EntryLine, but no result. I am facing an issue in above code itself, adding just a "Entry" in xaml and testing on IOS simulator works fine. 已经在Xamarin论坛上提出了同样的问题，但是没有找到任何答案 .

EDIT 1 - Added the complete stack layout.

使用 -

• Visual Studio 2017，Windows 10，Xamarin - 2.3.4.247 FormsToolKit - 1.1.18 IOS - MacBook Air 10.3